Safety railway signal torpedo and process of making the same



March 5, 1929. w, WEDGER 1,704,231

SAFETY RAILWAY SIGNAL TORPEDO AND PROCESS OF MAKING THE SAME Filed April18, 1927 n 22 ln eanToT. )6 L3 WulTer L..Wedger {8 M ATTys.

Patented Mar. 5, 1929.

UNITED STATES PATENT OFFIEE.

WALTER L. WEDGER, F BELMONT, MASSACHUSETTS, ASSIGNOR TO CENTRAL RAIL-WAY SIGNAL COMPANY, OF NEWTON, MASSACHUSETTS, A CORPORATION OF MAS-SACH'USETTS.

SAFETY RAILWAY SIGNAL TORPEDO AND PROCESS OF MAKING THE SAME.

Application filed April 18, 1927. Serial No. 184,493.

This invention relates to improvements in safety signal track torpedoesand the process of manufacture thereof.

The explosive composition heretofore used in railway signal torpedoescomprises essentially potassium chlorate as the oxidizing agent, sulphuras the reducing agent, common sand as an abrasive to generate frictionand increase sensitiveness to the impact of the locomotive wheel, anddextrine to serve as a binder when the explosive is moulded while inplastic form in or to fit the containers thereof.

One of the objects of the invention is to provide a railway signaltorpedo of greater efliciency, by the employment of a wellbalanced,chemical formula, constituting the explosive thereof, which develops alouder noise than has heretofore been obtained in 2 torpedoes of theusual weight and size used by railroads, and to provide a torpedopossessing greater stability to friction and concussion than those ofthe character above described.

This is accomplished in the present invention by employing potassiumperchlorate wholly or mainly in place of potassium chlorate as theoxidizing agent. Potassium perchlorate contains a larger amount ofavailable oxygen than potassium chlorate,

but is less sensitive and not liable to spon-' taneous ignition. Whenignited with sulphur, however, it produces a more powerful explosive byreason of the greater quantity of oxygen liberated to combine with thesulphur and other reducing ingredients which may be employed. Theincreased volume of noise produced bytorpedoes embodying the presentinvention insures the report being heard in the cab of the locomotive.The use of potassium perchlorate as the oxidizing agent of the explosivecomposition provides complete immunity from all danger of dissociationof the explosive ingredients during manufacture and subsequent storageand also prevents the possibility of what is termed en masse orsympathetic detonation to a very large extent.

In order to increase the sensitiveness of the torpedo a small quantityof a supplemental and more active agent than s'ulphur is employed, suchfor example, as antimony sul phide, or a small quantity of potassiumchlorate or both. When antimony sulphide is employed a more pronouncedflash is ob tained upon the detonation of the torpedo which serves as avisual signal in addition to the oral signal produced by the detonationof the torpedo.

It is well known by chemists that sulphur is liable to become acid whenexposed to the humidity of the atmosphere and that when such acidcomesin contact with a potassium chlorate explosive, spontaneousignition takes place. Therefore, regardless of the non-acid qualities ofthe sulphur in the explosive composition of a torpedo when manufacturedthere is every probability that if the torpedo is subjected to a humidatmosphere, slow generation of free acid will follow, and either causespontaneous ignition, or gradually reduce the oxygen from the potassiumchlorate, thereby rendering the torpedo inert.

Another object of the invention is to provide means for preventing theaction-of such acid upon the oxidizing agent. This is accomplished inthe present invention by introducing into the'explosive composition anantacid, to prevent the generation of acidity, preferably a smallquantity of an alkaline carbonate, such as calcium carbonate beingemployed. p

In some makes of torpedoes comprising an explosive composition embodyingsulphur and potassium chlorate as the active ingredients thereof,dextrine is omitted and the explosive enclosed in loose or granular formin suitable containers. But in explosive plastic compositions in whichdextrine is employed, and which are moulded to fit containers for thepurpose of convenience in handling and uniformity of charge, the.

explosive composition is moistened with water to reduce itssensitiveness to fire or explosion during the process of moulding, andalso to render the dextrine ingredient sufiicientl adhesive to hold theplastic in its moul ed form when dry. .Such an explosive composition,when dry, is sensitive to explosion from friction, or concussion, butwhen moistened with water becomes inert from such influences, and thisresults in the failure of the signal during service. To prevent thiscondition occuring during wet weather, it becomes necessary thoroughlyto waterproof the case or container of the explosive composition and itis found to be very diflicult to attain during manuvide a novel externalcoating for the torpedo, including the case, and the contents thereof,which is impervious to water, which furnishes a hard, tough covering forthe entire torpedo to enable it to withstand rough usage intransportation and handling while in service on railroads and which,during the manufacture, will harden or set more promptly than coatingsheretofore employed. Preferably a special. wax-like composition is usedwhich is hard at atmospheric temperature, but will flow readily whensubjected to a temperature well and safely below the lowest possibleignition temperature of the explosive composition. Whenthis coating isin a liquid state the torpedo may be dipped in it momentarily and thecoating will harden very quickly after removaltherefrom, thus avoidingthe long delay which is required for the evaporation of moisture orsolvents used in usual types of coatings for torpedoes. Furthermore,when the torpedo is coated by such composition its base can be placedupon a suitable sanding-board and the grains of sand thereupon willbecome partially, but firmly embedded in thecoating, thereby providing aroughened or abrasive base which will be less likely to slip upon therail. No further dipping or waterproofing is required and the usual leadstrap of the torpedo may be folded around it within a few minutes afterthe clipping is completed and the torpedo packed in a suitable case forshipment.

One of the principal objects of the invention is to provide a process ofmanufactur ing torpedoes in which the ingredients of the torpedo aremixed in a sufiicient amount of volatile liquid to permit the explosivecomposition to be poured into suitable moulds. By thus in effectsuspending the ingredients of the torpedo in a suitable volatile liquidduring the process of manufacture thereof, the maximum degree of safetyof manufacture is attained, and a much more uniform and homogeneouscomposition is produced when the composition is de-' posited from suchsuspension in the mould or the torpedo case by the vaporization of thesuspending liquid. Torpedoes poured and moulded in this manner can bereadily distinguished from other torpedoes by the smoothness of thesurface of the granular composition and by the uniformity of appearanceas readily as clay deposited from a free flowing mixture can bedistinguished from a granular mixture of clay in only a sufficientquantity of water to make it plastic and mouldable.

In the process of manufacturing torpedoes in accordance with the presentinvention I preferably employ a suitable alcohol in suflicient quantityto impart fluidity to the mixture of ingredients of the torpedo, suchfluidity preferably being approximately that of freely flowing molasses.By thus maintaining the mixture in a fluid condition a suitablewater-repellant material, such as a shellac solution in alcohol may beintroduced' into the liquid which, upon the evaporation of the liquid,will thoroughly impregnate the' ingredients of the explosive compositionand render the composition itself water-repellant and externalwaterproofing, therefore, unessential.

In the present manufacture of railway torpedoes employing potassiumchlorate Wholly as the oxidizing agent, heretofore described, greatdanger-fromflre andpossible explosion exists in the mixing and mouldingof the chlorate compound, especially should it become dry from thepartial evaporation of the water moistener, and the same danger existsin the handling of the dry plastics during the process of assembling thetorpedo.

I have discovered that where a volatile flammable liquid, such asalcohol, is employed in suflicient quantity to render the mixture fluid,as above described, and where the volatile liquid is subject to ignitionat a very low temperature upon approach of the flame, danger ofexplosion of the composition by ignition is prevented, as thevaporization caused by the flame maintains a tem-' perature at theexposed surface of the explosive mixture well belowthe ignitiontemperature of such mixture, and that the flame from the alcohol, orother liquid, can readily be extinguished by a fire extinguisher or by vwater, sand, or other usual means, thereby imparting a large measure ofsafety to the process of manufacture.

When the liquid composition above described is poured into the mould, orinto torpedo shell, as the case may be, the denatured alcohol, orvolatile liquid, very rapidly evaporates; consequently, the torpedoescan be manufactured much faster than those in; which. the composition ismade plastic .by'

the addition of dextrine and water and which usually require drying forseveral hours instead of the few minutes required for the evaporation ofthe alcohol. Furthermore such evaporation does not require applicationof heat above the usual room temperature.

An illustration of the torpedo embodying the invention and suitablemechanism for performing the process herein described is illustrated inthe accompanying drawings, in which,

Fig. 1 shows a series of torpedo cases ar ranged in a suitable supportwith a hopper and a suitable conduit leading therefrom for depositingthe flowing composition into the cases;

Fig. 2 illustrates the torptdo being dipped in the liquid wax-likecoating material;

- Fig. 3 shows the torpedoes after having been removed from the wax-likecomposition and deposited upon the sanding-board;

Fig. 4; is a longitudinal, diametrical, sectional view of a torpedoembodying the present invention;

Fig. 5 is a similar illustration of the torpedo at right angles to theconstruction illustrated in Fig. 1, showing the manner in which thestrap is secured to .the torpedo case;

Fig. 6 is a bottom plan view of the torpedo;

Fig. 7 is a plan View of a different form of torpedo case; and,

Fig. 8 is a longitudinal sectional view through 'a torpedo having thecasing illus trated in Fig. 7.

Torpedoes embodying the present invention, as heretofore stated,comprises potassium perchlorate as the oxidizing agent, sulphur as thereducing agent, white quartz or sand as the abrasive ingredient, andpreferably a small quantity of calcium carbonate as the antacid, anddesirably a small quantity of antimony sulphide as an additionalreducing agent. These materials, which are of granular form, desirablyare thoroughly mixed together in dry form and thereafter suspended in aVolatile liquid solution which serves to complete the homogeneity of themixture. The volatile liquid is permitted or caused to evaporate therebydepositing the granular ingredients as a residue in more intimatelymixed and homogeneous condition than has heretofore been accomplished.The torpedo thus produced may, therefore, be defined as comprising anexplosive granular composition of residual homogeneously depositedingredients there by distinguishing the more intimately mixed hunogeneouscomposition produced by such residual deposition from a liquidfrom usual compositions which are produced from a plastic mixture of theingredients.

Shellac desirablyis employed as a waterrepellant material and isdissolved in alcohol in the approximate proportion of one and one-halfpounds of shellac to one gallon of alcohol, denatured alcohol or woodalcohol. This solution of shellac in alcohol is added and stirred in theabove granular ingredients until the mixture attains a consistency offreely flowing molasses and the mass thoroughly stirred. If it isdesired to render the torpedo still more sensitive to the impact of thelocomotive wheel, a small quantity of a chemical more susceptible to theinfluence of friction and concussion, such as potassium chlorate orsimilar ingredient, may be added to act as a booster to the perchloratecompound. \Vhen the mixture has been stirred sufficiently to render itthoroughly homogeneous, it is placed in a receptacle or tank 1 fromwhich it is permitted to fiow into a preferably flexible tube 2 having asuitable nozzle 3. By pinching the tube between the thumb and fingersthe flow of the liquid composition from the nozzle can be controlled. Aseries of torpedo cases 4 may then be mounted upon a suitable table orsupport and the nozzle held over each torpedo case until it is filled.

In View of the contraction due to the evaporation of the solvent, it isusually desirable to fill the torpedo cases entirely full. Of course,suitable moulds may be employed for the explosive composition, insteadof the torpedo cases, and this is desirable in manufacturing certaintypes of torpedoes.

As soon as the torpedo cases have been filled evaporation of the solventbegins and in a very short time the alcohol, or other volatile liquid,will have evaporated. Such evaporation may, of course, be facilitated byexposure to artificial heat. As soon as the liquid has vaporized fromthe composition, the torpedoes may be coated. \Vhile such coating is notessential to torpedoes which have been impregnated with a Water-repellant material as herein described, it still is desirable as a furtherprotection to the torpedo, and also aids in securing the strap to thecasing, and further enables the base of the casing to be sanded. Afterthe torpedo case has been filled, the straps of the torpedo may be bentupwardly so that they can be conveniently grasped by the hand and thetorpedo 4 dipped in a bath 5 of a liquid wax-like coating compositioncontained in a receptacle 6.

A preferred coating composition comprises wax, rosin, a suitable binder,and red pigment, in such proportions to" become liquid at a relativelylow temperature such as one hundred twenty-five to one hundredforty-five degrees Fahrenheit. It should be sufliciently fluid when warmnot only to coat a fibrous casing, but to impregnate the edges thereofto a considerable depth. Such a composition will harden very quicklywhen exposed to usual atmospheric temperatures, such hardening usuallyrequiring from fifteen to twenty minutes. Thiscomposition at atmospherictemperatures is hard, but not brittle and forms an excellent protectivev coating bath 5 it desirably is placed base downwardly upon a layer ofsand 7 sprinkled over a sanding-board 8. As the coating is plastic, whenthe torpedo is thus placed upon the sand, the grains of sand becomepartially embedded in the coating so that when the coating hardens suchgrains of.

sand are firmly retained in it, but project a, suflicient distancetherefrom to present an abrasive surface such as is usually employed toprevent torpedoes from slipping upon the rail, but the sanding operationby this method is much more rapid than has heretofore been accomplishedWhere the coating composition comprises water or a solvent which must bevaporized.

. A desirable form of torpedo embodying the present invention isillustrated in Figs. 4 and 5 which comprises a cup-shaped, preferablycylindrical, receptacle or case 9 having the central portion 10 of itsbase de pressed and provided with apertures 11 and 12 to receive a usualstrap 13 of pliable or resilient metal, such as lead, or a spring havingsuitable means of attachment to the rail.

In View of the fact that the specifications for standard track torpedoconstructions promulgated by the American Railway Association requiresthat the explosive composition must not be in direct contact with anymetal portion of the torpedo, a fibre disk 14 is inserted in thereceptacle or case to prevent contact of the explosive composition withthe metal strap 13. The explosive composition 15 desirably is pouredinto the receptacle 14 thus formed in the manner above described andwhen hardened by the evaporation of the volatile liquid containedpresents a smooth surface by whichit can be readily recognized fromtorpedoes in which the explosive composition is prepared in plastic formin the usual manner heretofore employed.

Inasmuch as the explosive composition in the preferred form of torpedois impregnated with water-repellant.material it is unnecessary toprovide such a torpedo with usual waterproof coating. However, as amatter of practice, it is desirable to provide an exterior coating ofwax-likev material as above described in order to protect the torpedofrom'damagedn handling and also to provide means for securing to thebase of the torpedo an abrasive adaptedto reduce the likelihood ofslippage of the torpedo upon the rail.

The torpedo illustrated in Figs. 4 and 5 may, therefore, be coated andthe base thereof sanded in the manner above described, the sanded baseof the torpedo being illustrated in Fig. '6 of the drawing. A

Another form of torpedo, which may be made in accordance with thepresent inven-' tion, is illustrated in Figs. 7 and 8, in which Fig. 7illustrates a fibre casing in the general form of a Latin cross witha'central rectangular portion 16 having a spheroidal depression-17 toreceive a mass of the composition which desirably is previously preparedin suitable moulds by pouring the composition I into the same in themanner above described.

In constructing a torpedo of this type the explosive composition 18,which may have been previously moulded, is placed within the spheroidalcavity 17, the side flaps 19 and 20 are then folded over, and desirablyof such length that their free edges overlap when folded. The flap 21,having apertures 22 and 23 through which the strap 24 is threaded, isthen folded down upon the flaps 19 and 20 and finally the end flap 25 isfolded down upon the flap 21 as illustrated in Fig. 8. The torpedo caseis then coated preferably with a wax-like composition and the basethereof sanded in the manner above described.

It will be understood that various changes in the proportions of theingredients of the torpedo herein described may be made within the scopeof the invention herein defined by the claims and that in the process ofman ufacture suitable changes and modifications may be made in thematerials used and in the manner in which the same are treated Withinthe spirit and scope ofothe following claims.

' Having thus described the invention, what is claimed as new, anddesired to be secured by Letters Patent, is:

1. A composition for a railway signal torpedo comprising potassiumperchlorate as an oxidizing agent and sulphur as a reducing agent andalso containing a small quantity of a supplemental, more active reducingagent than sulphur.

2. A composition for a railway signal torpedo comprising potassiumperchlorate as an oxidizing agent and sulphur as a. reducing agent andalso containing a small quantity of a supplemental, more active reducingagent than sulphur, and also containing a small quantity of a more"sensitive oxidizing agent than potassium perchlorate.

3. A composition for a railway signal tor pedo comprising an explosivemixture containing sulphur, potassium perchlorate and a relatively smallquantity of antimony sulphide.

4;. A solid residual composition for a railway signal torpedo comprisinga homogeneous residual composition formed of intimately mixed granularreducing and oxidizing ingredients thoroughly impregnated with andunited by a water-repellant material and explosive only under theinfluence of friction or concussion.

5. A solid residual composition for a railway signal torpedo comprisin ahomo; geneous mixture of granular sulphur and potassium perchloratethoroughly impregnated with and united by a water-repellant material andexplosive under the influence of friction or concussion.

6. A solid residual composition for a railway signal torpedo comprisinga, homogeneous mixture of granular sulphur and potassium perchloratetogether with a relatively small quantity of potassium chlorate andexplosive under the influence of friction or concussion.

7. A solid residual composition for a railway signal torpedo comprisinga homogeneous mixture of granular sulphur and potassium perchloratetogether with relatively small quantities of potassium chlorate andantimony sulphide. 1

8. A railway signal torpedo having a shell containing a solidhomogeneous composition comprising a granular mixture of sulphur andpotassium perchlorate and impregnated with a shellac solution in alcoholand explosive under the influence of friction or concussion. i

9. 'A railway signal torpedo having a shell containing a solid mass ofexplosive composition comprising a granular mixture of sulphur andpotassium perchlorate intimately associated with each other and with anantacid and impregnated with and united by'a water-repellant material.

10. The process of safely manufacturing an explosive granularcomposition which consists in mixing the ingredients of said explosivecomposition while suspended in a volatile slow burning, flammableliquid, ignitable upon approach of a flame at a temperature well belowthe temperature of ignition of said explosive mixture.

, 11. The process of safely manufacturing a normally stable, but,explosive composition which consists irfenveloping the exposed surfaceof the ingredients of said composition during manufacture, in a slowburning'flammable vapor which will not readily communicate fire to theexplosive.

12. The process of manufacturing torpedoes and the like which comprisesmixing the ingredients of a granular or powdered explosive mixture in aslow burning flammable volatile liquid suflicient in quantity to enablethe mixture to flow readily, pouring the same into suitable moulds andcausing the vaporization of said volatile liquid.

13. The process of manufacturing torpedoes and the like which comprisesmixing the 1 ingredients of an explosive mixture in alcohol sufiicientin quantity to enable the mixture to flow readily,'pouring the same intosuitable moulds and causing the vaporization of the said liquid. X

In testimony whereof. I have signed my name to this specification.

WALTER L. WEDGER.

